Recent Advances in the Field of Integral Equation Theories: Bridge Functions and Applications to Classical Fluids

Abstract

We offer a nonexhaustive presentation of the advances in the field of the integral equation theories (IETs) in terms of bridge functions, by describing their application to the determination of structural and thermodynamic properties of simple fluids. After having exposed some basic necessary definitions in the structural description of fluid systems, various IETs are first presented, by recalling their basic expressions and underlying physical assumptions. In this context, a special attention is devoted to the thermodynamic consistency concept, and to the role that this natural constraint plays with the improvement of their performances. In this framework, we shall have as a specific purpose in this presentation to investigate the r– and q–space structural predictions of the IETs together with their relationship with thermodynamics. It is already known that these older theories, that provide in principle a direct source of information, yield however only qualitative agreement for correlation functions, because of suffering of a severe thermodynamic inconsistency. Improved closure relations, the self-consistent integral equation theories (SCIETs) are then introduced. Their applications are examined and systematically compared against related computer simulation data, when available. Satisfying to a single thermodynamic 2 jean-marc bomont